Multi-chamber medical bags have been used for years for the preparation of mixed solutions. Known multi-chamber bags have different systems as separation arrangements between the chambers.
One of these containers uses breakable separation parts made of rigid, breakable materials. These have the advantages of largely universal applicability, but have disadvantages to the extent that the mixing opening has a limited cross section and undesirable particle formation may occur upon breakage of the separation arrangement. Other containers make use of peelable heatsealed welds for the separation of the fluids. These containers are flexible bags made of polymer films.
International Publication Number WO 98/10733 describes a container including three chambers for storing medical components that are mixed together to create a final medical solution. The container comprises an upper circumference region provided with means for hanging up the container and a lower circumference region provided with a port system for introducing further medical fluids and dispensing the final medical solution. The first chamber is arranged in the left side portion, the second chamber in the middle side portion and the third chamber in the right side portion of the container. The first peelable seal separating the first chamber from the second chamber as well as the second seal separating the second chamber from the third chamber are arranged in vertical directions. The triple-chamber bag is filled with components for preparing a parenteral nutrition. For administration of the parenteral nutrition the container is grasped firmly on each side and the container is firmly squeezed. The squeezing is continued until the peelable seals are fully open. After mixing the medical components the container is ready for use. An alternative method includes the step of placing the container on a flat table and rolling up the bag by hand starting from the top of the container until the peelable seals are fully open. Both opening methods result in a rapid mixing of the medical components at the same time. Both opening methods of the container do not allow in a first step mixing of the component of the first chamber with the component of the second chamber and in a second step mixing of the components of the first and second compartments with the component of third compartment.
International Publication Number WO 98/16183 discloses another flexible container with three chambers for the separated storage of the ingredients of preparations for parenteral use, namely carbohydrates within the first chamber, lipids within the second chamber, and an amino acid within the third chamber. The chambers are separated by peelable seals which can be opened sterilely from the outside. The compartments are arranged such that a rapid and complete mixing of all ingredients is possible by simply opening the connecting means. After removing the bag from an overpouch, the upper chamber is pressed by hand to mix the glucose and amino acid solutions. Following the mixing of these ingredients the lipid chamber is pressed to open the next peelable seal. The contents are mixed thoroughly by gently agitating the bag several times. The order in which the components are mixed depends on the order of pressing the compartments. Therefore, the user has to take care pressing the chambers in the correct order.
European patent document EP 0 893 982 B1 describes a container for storage of oxygen sensitive parenterally administerable agents comprising a primary container enclosed in an oxygen impermeable envelope. The container is separated into an upper chamber, a middle chamber and a lower chamber by two horizontal peelable seals. The seals can be opened by different handling techniques. The chambers and seals are arranged such that the container allows mixing of the components in a controlled order, i.e. the components of the upper and middle compartment are mixed before mixing the components of the middle and lower compartment. The designation of the chambers for the nutrients has to be done after careful consideration of both convenience and safety aspects. As such, it is preferred that either amino acid solution or lipid solution is contained in the bottom chamber, since, if the user for some reason, would be unsuccessful in correctly performing the mixture procedure, the infusion of a pure amino acid or lipid solution leaves the patient uneffected compared to the accidental infusion of pure glucose solution, which could lead to unwanted side effects, for instance, if the patient suffers from complications related to diabetes.
The most frequent complaint from customers using flexible multi-chamber bags made of polymer films is that the film is torn when the weak seal is opened. The danger of tearing the film depends on the opening technique as well as the properties of the film and the filling, sterilization and transportation process.
U.S. Pat. No. 6,017,598 suggests that peelable seals for separating the chambers should be separable with a force in the range from 5 to 20 N. If the seam is separable with a force of less than 5 N, no reliable separation of the chambers is possible, since the bond can release by itself, for example, as a result of slight shocks during transport which exert pressure on one or a plurality of chambers. At a force of 20 N, the seam can be separated only with great difficulty. There is a danger that instead of the seam, the film will tear and the bag will leak.
The two most common complaints concerning medical containers with a peelable seal are: (1) peelable seals are already opened at arrival to customer and (2) a film failure when opening peelable seals.
Since flexible containers with peelable seals of low seal strength, e.g. 5-10 N, can be damaged during manufacturing and transport, weak seals are usually protected by folding the bag. Generally, the peelable seal strength should be high enough for production and transport and still low enough to easily open the bag.
In order to simplify the opening of peelable seals, such seals have been provided with so-called rupture zones, whereby the opening force is locally reduced and the manual opening of the peelable seals is facilitated. Such seals can readily be opened by different handling techniques.
European patent document EP 0 700 280 suggests a V-shaped rupture zone. In this case, the seal opens first at the point of the V since the highest force on the seal is created there.
The container as disclosed in European patent document EP 0 893 982 comprises peelable seals having rupture zones. The rupture zones of the peelable seals are V-shaped and, therefore, comprise a point where two straight seams meet in an angle. A small or sharp angle will be easy to rupture by the user, but it will at the same time create a risk for unintentional opening when handling the container. In contrast, a very large angle will provide a seam that is difficult to open. Therefore, EP 0 893 982 suggests an angle of the seals in the rupture zone of 120° to 140°.
A first preferred opening procedure mentioned in European patent document EP 0 893 982 is to gently roll up the container from the upper side and thereby make use of the volume of the largest chamber to exert a pressure large enough to rupture the seal in its weakest point and peel apart the seam towards the sides of the container. This technique is designated as the rolling method. Another preferred way of opening the seal is to pull the front and the rear walls of the inner container apart from one another by a careful pulling motion so a rupture is formed in the weakest spot of the seal which thereby may be easy to peel apart. This technique is designated as the pulling method.
Rolling up the bag from the upper portion towards the lower portion is a safer opening method; however, most flexible containers with peelable seals are difficult to open by the rolling technique.